The primary objective of this research proposal is mapping and characterization of genes that contribute to epilepsy. This is achieved by studying epileptic individuals who have balanced chromosomal rearrangement with a breakpoint in a locus implicated in epilepsy. Three such cases, DGAP095, 097 and 131 (dgap.harvard.edu), are being investigated in this proposal. Analysis of breakpoints in DGAP095 showed that the DGKD gene is disrupted by rearrangement at the 2q37 locus, which maps near one of the seizure susceptibility loci in humans. We propose that DGKD disruption is pathogenetic to the seizure phenotype exhibited by the patient in light of the (1) implication of diacylglycerol kinases in neural signaling, (2) murine DGKD localization near a seizure susceptibility locus, and (3) DGKD expression in developing CNS in model organisms. DGKD ortholog expression will be assessed in various sections of the mouse brain, and studies confirming the etiologic role of DGKD will include construction of a mouse model. In DGAP097 and 131, breakpoints Xp22.1 and 5q13 lie near epilepsy implicated loci. They will be positioned on the human genome map using fluorescence in situ hybridization and the sequence at the breakpoints will be analyzed in a search for potential candidate genes, if the breakpoint falls within a gene-coding region, Northern blot analyses will be used to assess the presence or absence of novel transcript(s) due to the rearrangement. A prospective mutation scan in families with epilepsy /inked to the locus of interest as well as in patients with epilepsy inherited in an autosomal dominant fashion is a future direction of this research, and could be done using single-stranded conformation polymorphism or denaturing gradient gel electrophoresis with subsequent sequencing of aberrant PCR fragments.